Add 'compiler/rustc_codegen_cranelift/' from commit '793d26047f994e23415f8f6bb5686ff25d3dda92'
git-subtree-dir: compiler/rustc_codegen_cranelift git-subtree-mainline:cf798c1ec6git-subtree-split:793d26047f
This commit is contained in:
bjorn3
206
compiler/rustc_codegen_cranelift/src/backend.rs
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206
compiler/rustc_codegen_cranelift/src/backend.rs
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//! Abstraction around the object writing crate
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use std::convert::{TryFrom, TryInto};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_session::Session;
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use cranelift_module::FuncId;
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use object::write::*;
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use object::{RelocationEncoding, RelocationKind, SectionKind, SymbolFlags};
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use cranelift_object::{ObjectBuilder, ObjectModule, ObjectProduct};
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use gimli::SectionId;
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use crate::debuginfo::{DebugReloc, DebugRelocName};
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pub(crate) trait WriteMetadata {
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fn add_rustc_section(&mut self, symbol_name: String, data: Vec<u8>, is_like_osx: bool);
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}
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impl WriteMetadata for object::write::Object {
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fn add_rustc_section(&mut self, symbol_name: String, data: Vec<u8>, _is_like_osx: bool) {
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let segment = self
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.segment_name(object::write::StandardSegment::Data)
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.to_vec();
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let section_id = self.add_section(segment, b".rustc".to_vec(), object::SectionKind::Data);
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let offset = self.append_section_data(section_id, &data, 1);
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// For MachO and probably PE this is necessary to prevent the linker from throwing away the
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// .rustc section. For ELF this isn't necessary, but it also doesn't harm.
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self.add_symbol(object::write::Symbol {
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name: symbol_name.into_bytes(),
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value: offset,
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size: data.len() as u64,
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kind: object::SymbolKind::Data,
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scope: object::SymbolScope::Dynamic,
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weak: false,
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section: SymbolSection::Section(section_id),
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flags: SymbolFlags::None,
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});
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}
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}
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pub(crate) trait WriteDebugInfo {
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type SectionId: Copy;
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fn add_debug_section(&mut self, name: SectionId, data: Vec<u8>) -> Self::SectionId;
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fn add_debug_reloc(
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&mut self,
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section_map: &FxHashMap<SectionId, Self::SectionId>,
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from: &Self::SectionId,
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reloc: &DebugReloc,
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);
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}
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impl WriteDebugInfo for ObjectProduct {
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type SectionId = (object::write::SectionId, object::write::SymbolId);
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fn add_debug_section(
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&mut self,
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id: SectionId,
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data: Vec<u8>,
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) -> (object::write::SectionId, object::write::SymbolId) {
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let name = if self.object.format() == object::BinaryFormat::MachO {
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id.name().replace('.', "__") // machO expects __debug_info instead of .debug_info
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} else {
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id.name().to_string()
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}
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.into_bytes();
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let segment = self.object.segment_name(StandardSegment::Debug).to_vec();
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// FIXME use SHT_X86_64_UNWIND for .eh_frame
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let section_id = self.object.add_section(
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segment,
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name.clone(),
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if id == SectionId::EhFrame {
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SectionKind::ReadOnlyData
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} else {
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SectionKind::Debug
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},
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);
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self.object
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.section_mut(section_id)
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.set_data(data, if id == SectionId::EhFrame { 8 } else { 1 });
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let symbol_id = self.object.section_symbol(section_id);
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(section_id, symbol_id)
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}
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fn add_debug_reloc(
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&mut self,
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section_map: &FxHashMap<SectionId, Self::SectionId>,
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from: &Self::SectionId,
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reloc: &DebugReloc,
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) {
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let (symbol, symbol_offset) = match reloc.name {
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DebugRelocName::Section(id) => (section_map.get(&id).unwrap().1, 0),
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DebugRelocName::Symbol(id) => {
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let symbol_id = self.function_symbol(FuncId::from_u32(id.try_into().unwrap()));
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self.object
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.symbol_section_and_offset(symbol_id)
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.expect("Debug reloc for undef sym???")
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}
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};
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self.object
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.add_relocation(
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from.0,
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Relocation {
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offset: u64::from(reloc.offset),
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symbol,
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kind: reloc.kind,
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encoding: RelocationEncoding::Generic,
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size: reloc.size * 8,
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addend: i64::try_from(symbol_offset).unwrap() + reloc.addend,
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},
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)
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.unwrap();
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}
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}
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// FIXME remove once atomic instructions are implemented in Cranelift.
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pub(crate) trait AddConstructor {
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fn add_constructor(&mut self, func_id: FuncId);
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}
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impl AddConstructor for ObjectProduct {
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fn add_constructor(&mut self, func_id: FuncId) {
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let symbol = self.function_symbol(func_id);
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let segment = self
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.object
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.segment_name(object::write::StandardSegment::Data);
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let init_array_section =
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self.object
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.add_section(segment.to_vec(), b".init_array".to_vec(), SectionKind::Data);
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let address_size = self
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.object
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.architecture()
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.address_size()
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.expect("address_size must be known")
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.bytes();
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self.object.append_section_data(
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init_array_section,
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&std::iter::repeat(0)
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.take(address_size.into())
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.collect::<Vec<u8>>(),
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8,
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);
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self.object
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.add_relocation(
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init_array_section,
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object::write::Relocation {
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offset: 0,
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size: address_size * 8,
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kind: RelocationKind::Absolute,
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encoding: RelocationEncoding::Generic,
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symbol,
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addend: 0,
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},
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)
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.unwrap();
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}
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}
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pub(crate) fn with_object(sess: &Session, name: &str, f: impl FnOnce(&mut Object)) -> Vec<u8> {
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let triple = crate::build_isa(sess, true).triple().clone();
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let binary_format = match triple.binary_format {
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target_lexicon::BinaryFormat::Elf => object::BinaryFormat::Elf,
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target_lexicon::BinaryFormat::Coff => object::BinaryFormat::Coff,
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target_lexicon::BinaryFormat::Macho => object::BinaryFormat::MachO,
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binary_format => sess.fatal(&format!("binary format {} is unsupported", binary_format)),
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};
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let architecture = match triple.architecture {
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target_lexicon::Architecture::X86_32(_) => object::Architecture::I386,
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target_lexicon::Architecture::X86_64 => object::Architecture::X86_64,
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target_lexicon::Architecture::Arm(_) => object::Architecture::Arm,
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target_lexicon::Architecture::Aarch64(_) => object::Architecture::Aarch64,
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architecture => sess.fatal(&format!(
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"target architecture {:?} is unsupported",
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architecture,
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)),
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};
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let endian = match triple.endianness().unwrap() {
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target_lexicon::Endianness::Little => object::Endianness::Little,
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target_lexicon::Endianness::Big => object::Endianness::Big,
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};
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let mut metadata_object = object::write::Object::new(binary_format, architecture, endian);
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metadata_object.add_file_symbol(name.as_bytes().to_vec());
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f(&mut metadata_object);
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metadata_object.write().unwrap()
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}
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pub(crate) fn make_module(sess: &Session, name: String) -> ObjectModule {
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let mut builder = ObjectBuilder::new(
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crate::build_isa(sess, true),
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name + ".o",
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cranelift_module::default_libcall_names(),
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)
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.unwrap();
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if std::env::var("CG_CLIF_FUNCTION_SECTIONS").is_ok() {
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builder.per_function_section(true);
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}
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let module = ObjectModule::new(builder);
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module
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}
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